来自两个表的JSON数据，不重复连接表主键

I have two models:

Category Model has: id PRIMARY_KEY, category_name, ...

Item Model has: id PRIMARY_KEY, item_name, category_id (is id on category table), ...

I wish to achieve this JSON response:

Item:
{
    "id": 1,
    "item_name": "some item name",
    "category": {
        "id": "5",
        "category_name": "some category name"
    }
}

So far I have managed to achieve only response:

{
    "id": 1,
    "item_name": "some item name",
    "category_id": "5", // i dont want it to appear here!
    "category": {
        "id": "5",
        "category_name": "some category name"
    }
}

With query:

$data = Item::select('id', 'item_name', 'category_id')->with(['category' => function ($query) {
            $query->select('id', 'category_name');
        }])->get();
return response()->json($data);

I tried select('id', 'item_name') instead of select('id', 'item_name', 'category_id'), but it fails, since it required 'category_id' for with to work. Any clean solutions to this?

The solution was to make it hidden in Collection:

$data = Item::select('id', 'item_name', 'category_id')->with(['category' =>     function ($query) {
            $query->select('id', 'category_name');
        }])->get()->makeHidden('category_id');
return response()->json($data);

Yes you cannot remove category_id as it's needed to create the relationship. You can instead do something like this after you query and set $data.

$response = [];
$data->each(function ($value) use (&$response) { // pass $response by reference
    unset($value->category_id);
    $response[] = $value;
});
return response()->json($response);